as for the joysticks I dont agree to buy u360s but its your decision
Everybody is entitled to their opinion, but if you are going to post something like this it would probably be more useful to the OP if you said
why you don't agree...
Anyhow, to the OP,
You have a good basic setup there. Different people have different priorities in terms of admin buttons. Don't forget you can always use the shift functionality of the ipac for additional admin functions.
I don't have any experience with the inserts, but it looks like they are designed to fit in a standard happ-like translucent button. You asked about "basic" buttons, so if you mean the standard non-translucent one then you will probably have a hard time seeing the inserts

As for wiring,
The u360's just connect straight to usb (pretty sure they come with the necessary cables.) If you want to connect the buttons to the sticks instead of the ipac then you will probably want to buy the harness along with the sticks.
Wiring buttons to the ipac is easy enough. Just get some basic 22ish-gauge wire (stranded hookup wire) and some crimp on quick-disconnects. If you need the crimp tool as well you can just buy ultimarc's wiring kit. It has all of the above, though depending on the microswitches you use you might need to get some different sized disconnects.